In recent years, due to high oil prices and environmental issues, the microbial production of biofuels has attracted a great deal of attention. Also, as biofuels have been considered as alternative fuels to fossil fuels, their market size has increased rapidly. Particularly, alkane has properties suitable for use as fuel, including high energy density, controllable volatility, a sufficient octane number and a low impurity content, and has advantages over ethanol in that it has higher energy efficiency and is more readily miscible with gasoline. In addition, alkane can be used in existing oil pipelines or automobile engines. Thus, if alkane which is the most suitable alternative fuel is produced in large amounts using microorganisms, the import of crude gas can be reduced and the emission of greenhouse gas can be reduced, resulting in environmental effects.
Currently, commercially available gasoline is a linear hydrocarbon compound having 6-10 carbon atoms in one molecule and containing a direct carbon-carbon bond and a straight-chain structure coexisting with a branched-chain structure.
In addition, it contains energy of about 40 MJ per kg, is likely to evaporate at room temperature and atmospheric pressure and has easy and significant inflammability. The most key factor of gasoline is octane number. Some hydrocarbons having a highly branched structure are smoothly burned in the automobile engine, whereas hydrocarbons having an unbranched carbon chain are likely to explode in the cylinder to cause the piston to move intensively. This undesirable explosion causes knocking phenomena in automobiles. As a measure for quantifying this knocking property, the octane number of isooctane (2,2,4-trimethylpentane) which is a high-quality fuel having a highly branched structure is set at 100, and the octane number of heptane which is a low-quality automobile fuel is set at 0. Under this system, a regular grade gasoline has an octane number of about 87. For this reason, it will be important to produce large amounts of highly branched hydrocarbons, which are the key materials in gasoline, such as isooctane.
Usually, the ratio of gasoline in crude oil is only 25%, and this portion is most frequently used as fuel. Thus, in order to increase the production of gasoline in petrochemical plants, a C12-C18 fraction having a high boiling point is subjected to a cracking process to produce a fraction having a small carbon number and a low boiling point. From this viewpoint, when a fraction of a relatively large carbon number corresponding to kerosene or diesel range fuel is reformed by thermal and catalytic cracking into gasoline in an oil refinery. Studies on the microbial production of hydrocarbons started to increase gradually from studies on the isolation of hydrocarbon-like substances from the cells of marine bacteria and algae due to the development of gas-liquid chromatography. Studies on the microbial production of hydrocarbons can be largely divided into two categories: a method related to intracellular hydrocarbons of microorganism, and a method related to extracellular hydrocarbons of microorganism. With respect to intracellular production, there is a wide variety of systematic groups of microorganisms, which usually show a value of about 0.005-2.69% on a dry mass basis. Strains capable of producing hydrocarbons by this method include cyanobacteria, anaerobic phototrophic bacteria, gram-negative anaerobic sulfate-reducing bacteria, gram-negative facultatively anaerobic bacteria, yeasts, fungi and the like. Each of the strains can produce hydrocarbons of various profiles and shows a unique fraction and predominance. In studies on extracellular production, strains having the ability to produce hydrocarbons include Desulfovibrio and Clostridium, and strains having the ability to produce isoprene which is a volatile non-methane hydrocarbon include Actinomycetes, and strains having the ability to produce ethylene include Aspergillus clavatus. 
Thus, there have been studies on the optimization of culture conditions in industrially applicable strains capable of producing hydrocarbons, studies on key materials such as hydrocarbon-related genes and enzymes, and studies on metabolic fluxes. However, studies on the analysis of genes and enzymes and the application of metabolic engineering are still insufficient. Thus, a more fundamental approach is required to screen industrially applicable strains, analyze genes associated with the production of target hydrocarbons and isolate metabolic flux-related enzymes from these strains to optimize hydrocarbon production processes, thereby increasing the productivity of hydrocarbons.
Accordingly, the present inventors have made extensive efforts to develop a novel method for microbial production of hydrocarbons, including alkane, and as a result, have constructed a microorganism variant improved so as to suitable for the production of hydrocarbons, including alkane, by constructing a new metabolic pathway that converts fatty acid as a substrate to alkane, and have found that the microorganism variant is useful for the production of alkanes, including octane, nonane and nonene, which are gasoline-range alkanes, as well as pentadecane and heptadecane, thereby completing the present invention.